package org.apache.lucene.analysis;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.io.Reader;

import org.apache.lucene.util.AttributeSource;
import org.apache.lucene.util.Version;

/**
 * LowerCaseTokenizer performs the function of LetterTokenizer
 * and LowerCaseFilter together.  It divides text at non-letters and converts
 * them to lower case.  While it is functionally equivalent to the combination
 * of LetterTokenizer and LowerCaseFilter, there is a performance advantage
 * to doing the two tasks at once, hence this (redundant) implementation.
 * <P>
 * Note: this does a decent job for most European languages, but does a terrible
 * job for some Asian languages, where words are not separated by spaces.
 * </p>
 * <p>
 * <a name="version"/>
 * You must specify the required {@link Version} compatibility when creating
 * {@link LowerCaseTokenizer}:
 * <ul>
 * <li>As of 3.1, {@link CharTokenizer} uses an int based API to normalize and
 * detect token characters. See {@link CharTokenizer#isTokenChar(int)} and
 * {@link CharTokenizer#normalize(int)} for details.</li>
 * </ul>
 * </p>
 */
public final class LowerCaseTokenizer extends LetterTokenizer {

    /**
     * Construct a new LowerCaseTokenizer.
     * 
     * @param matchVersion
     *          Lucene version to match See {@link <a href="#version">above</a>}
     * 
     * @param in
     *          the input to split up into tokens
     */
    public LowerCaseTokenizer(Version matchVersion, Reader in) {
        super(matchVersion, in);
    }

    /** 
     * Construct a new LowerCaseTokenizer using a given {@link AttributeSource}.
     *
     * @param matchVersion
     *          Lucene version to match See {@link <a href="#version">above</a>}
     * @param source
     *          the attribute source to use for this {@link Tokenizer}
     * @param in
     *          the input to split up into tokens
     */
    public LowerCaseTokenizer(Version matchVersion, AttributeSource source, Reader in) {
        super(matchVersion, source, in);
    }

    /**
     * Construct a new LowerCaseTokenizer using a given
     * {@link org.apache.lucene.util.AttributeSource.AttributeFactory}.
     *
     * @param matchVersion
     *          Lucene version to match See {@link <a href="#version">above</a>}
     * @param factory
     *          the attribute factory to use for this {@link Tokenizer}
     * @param in
     *          the input to split up into tokens
     */
    public LowerCaseTokenizer(Version matchVersion, AttributeFactory factory, Reader in) {
        super(matchVersion, factory, in);
    }

    /**
     * Construct a new LowerCaseTokenizer.
     * 
     * @deprecated use {@link #LowerCaseTokenizer(Version, Reader)} instead. This will be
     *             removed in Lucene 4.0.
     */
    @Deprecated
    public LowerCaseTokenizer(Reader in) {
        super(Version.LUCENE_30, in);
    }

    /**
     * Construct a new LowerCaseTokenizer using a given {@link AttributeSource}.
     * 
     * @deprecated use {@link #LowerCaseTokenizer(Version, AttributeSource, Reader)}
     *             instead. This will be removed in Lucene 4.0.
     */
    @Deprecated
    public LowerCaseTokenizer(AttributeSource source, Reader in) {
        super(Version.LUCENE_30, source, in);
    }

    /**
     * Construct a new LowerCaseTokenizer using a given
     * {@link org.apache.lucene.util.AttributeSource.AttributeFactory}.
     * 
     * @deprecated use {@link #LowerCaseTokenizer(Version, AttributeSource.AttributeFactory, Reader)}
     *             instead. This will be removed in Lucene 4.0.
     */
    @Deprecated
    public LowerCaseTokenizer(AttributeFactory factory, Reader in) {
        super(Version.LUCENE_30, factory, in);
    }

    /** Converts char to lower case
     * {@link Character#toLowerCase(int)}.*/
    @Override
    protected int normalize(int c) {
        return Character.toLowerCase(c);
    }
}
